Multiple choke coil and electronic equipment using the same

ABSTRACT

The invention is comprised of a coil group arranging a plurality of terminal-integrated type coils ( 1 ), ( 4 ) formed by bending a metal sheet in a preset development form and having a predetermined positional relationship, and a magnetic material ( 7 ) burying therein the coil group. For example, axes of the plurality of coils ( 1 ), ( 4 ) constituting the coil group, are arranged in parallel wherein the center point of at least one coil selected from the plurality of coils ( 1 ), ( 4 ) and the center point of a coil other than the selected coil are in an staggered arrangement. Due to this, an array type choke coil can be realized which is thin overall and operable with a large current in a high frequency band.

TECHNICAL FIELD

The present invention relates to an array type choke coil for use invarious electronic apparatuses and to an electronic apparatus usingsame, particularly a power supply apparatus.

BACKGROUND ART

In inductors such as choke coils, there is a desire for size andthickness reduction in order to cope with size and weight reduction ofelectronic apparatuses. For speed and integration increase in LSIs suchas CPUs, the inductor is desired for use on large current at severalamperes to several tens of amperes in the high frequency region.

Accordingly, there is a desire to inexpensively supply an inductor whichis reduced in size and lowered in electric resistance for suppressingheat generation, reduced in loss in high-frequency region and less ininductance value lowering due to direct current superimposition even onlarge current.

Recently, in DC/DC converters or the like, a circuit scheme called themulti-phase scheme is adopted as a power supply circuit for achievingcurrent increase in the high-frequency band. This circuit scheme is ascheme for sequential operation in parallel by use of a switch whilephase-controlling a plurality of DC/DC converters. This scheme has afeature capable of realizing the reduction of ripple currents andincrease of current in the high-frequency band with efficiency.

However, the above circuit structure solely is not necessarilysufficient in realizing the increase of current in the high-frequencyband. For the choke coil for use on such a power supply circuitapparatus, size reduction and current increase in the high-frequencyband is required.

In respect of such a problem, the choke coil disclosed inJP-A-2002-246242 is structured in that in a magnetic material is burieda hollow-cored coil formed by winding in a coil form a conductor wirehaving an insulation film such as of polyurethane. This magneticmaterial is made by solidifying magnetic powder whose surface is coatedwith two kinds or more of resin materials. The magnetic material isfitted with a metal terminal worked by bending. The hollow-cored coiland the metal terminal are electrically connected together by welding,soldering or a conductive adhesive or the like.

However, the conventional choke coil structure requires post-fixing of ametal terminal, making it difficult to reduce direct-current resistancevalue. Meanwhile, arranging the foregoing coils in pluralitycorresponding to the number of multi-phases results in an increasedsetup space, making size reduction difficult. Furthermore, in the caseof use in multi-phase, there is a problem that characteristic cannot befully exhibited because of inductance variation between the plurality ofcoils.

Meanwhile, when using in the multi-phase scheme a hollow-cored coilformed by winding in a coil form a conductor wire having an insulationfilm such as of polyurethane, in case a plurality of hollow-cored coilsare vertically arranged in line, for example, the total height isincreased thus making it impossible to reduce the thickness.Furthermore, such a hollow-cored coil requires to increase the number ofturns in order to increase the inductance value, raising a problem ofsize-increasing of the choke coil itself.

DISCLOSURE OF THE INVENTION

The present invention is for solving these problems, and it is an objectthereof to provide an array type choke coil which is excellent indirect-current superimposition characteristic, operable on large currentwhile securing the inductance value in high-frequency band, and capableof being reduced in size.

An array type choke coil of the present invention has a structurecomprising: a coil group in which a plurality of terminal-integratedtype coils formed by bending a metal sheet in a preset development formare arranged to have a set positional relationship; and a magneticmaterial burying therein the coil group. Due to this structure, the coilparts of a plurality of terminal integrated type coils are buried in aninsulative magnetic material. Therefore, it is possible to obtain anarray type choke coil favorable in characteristic in high-frequencyband, small in inductance value variation and less in short circuitoccurrence, and excellent in producibility.

An array type choke coil of the present invention may be structured inthat the plurality of coils constituting the coil group are arrangedsuch that the axes thereof are set the coils in parallel, and also acenter point of at least one coil selected from the plurality of coilsand a center point of a coil other than the selected coil are arrangedto be staggered. This can realize an array type choke coil which issmall in size, capable of providing a high coupling and capable ofcoping with a large current.

In the above structure, the structure may be such that a predeterminedinductance value is obtained by changing a distance between a centerpoint of at least one coil selected from the coil group and a centerpoint of at least one coil selected from the plurality of coils otherthan the selected coil. Otherwise, the structure may be such that apredetermined inductance value is obtained by changing a height of acenter point of at least one coil selected from the coil group and acenter point of at least one coil selected from the plurality of coilsother than the selected coil. This structure can easily realize asmall-sized short-structured array type choke coil having coils equal inthe number of turns but different in inductance value.

In the above structure, the structure may be such that at least one coilselected from the coil group and both coils immediately adjacent to theselected coil are in a V-form or inverted V-form arrangement, to make adirection of a magnetic flux extending through the coil caused upon flowof a current to the selected coil and a direction of a magnetic fluxextending through the coil caused upon flow of a current to the bothcoils arranged immediately adjacent different in direction from eachother. This structure can realizes an array type choke coil small insize while increasing the inductance value.

In the above structure, the structure may be such that at least one coilselected from the coil group and both coils immediately adjacent to theselected coil are in a V-form or inverted V-form arrangement, to make adirection of a magnetic flux caused upon flow of a current to theselected coil and a direction of a magnetic flux caused upon flow of acurrent to the both coils arranged immediately adjacent same indirection. This structure can realize an array type choke coil excellentin direct-current superimposition characteristic and structured smalland short.

In the above structure, the structure may be such that the coilsconstituting the coil group have the number of turns of (N+0.5) turns(where N is an integer equal to or greater than 1), to provide anarrangement structure of stacking an N-turn portion of the coil selectedfrom the coil group and an (N+0.5)-turn portion of the coil immediatelyadjacent to the selected coil. This structure can realize an array typechoke coil structured small and short.

In the above structure, the structure may be such that a predeterminedinductance value is obtained by changing respective distances between acenter point of the coil selected and center points of the both coilsarranged immediately adjacent. This structure can easily realize asmall-sized array type choke coil equal in the number of turns of thecoil but different in inductance value.

In the above structure, the structure may be such that the center pointsof the plurality of coils constituting the coil group are on a sameplane. This can realize an array type choke coil less in inductancevalue variation between a plurality of coils, short in structure, andcapable of coping with large current and frequency increase.

In the above structure, the structure may be such that a predeterminedinductance value is obtained by changing a distance between centerpoints of two coils immediately adjacent among the plurality of coils.This can easily realize an array type choke coil using coils equal inthe number of turns but different in inductance value.

In the above structure, the structure may be such that the coil group isarranged such that magnetic fluxes in the coils caused upon flowingcurrents respectively to the plurality of coils alternate in direction.This can realize an array type choke coil great in inductance value dueto the respective magnetic fluxes being superimposed.

In the above structure, the structure may be such that the coil group isarranged such that magnetic fluxes in the coils caused upon flowingcurrents respectively to the plurality of coils are same in direction.This can realize an array type choke coil excellent in direct-currentsuperimposition characteristic because of capability of suppressingmagnetic flux saturation.

The array type choke coil of the present invention is structured, in theabove structure, such that the center axes of the plurality of coilsconstituting the coil group are arranged in parallel, distance between acenter point of at least one coil selected from the plurality of coilsand a center point of a coil immediately adjacent to the selected coilis a half or smaller than the sum of an outer diameter of the selectedcoil and a diameter of the adjacent coil, and at least one turn portionof the selected coil is arranged in a manner meshing with the adjacentcoil. This structure can realize an array type choke coil small in size,capable of providing a high coupling and capable of coping with a largecurrent.

In the above structure, the structure may be such that the selected coiland the adjacent coil have the number of turns of N turn (where N is aninteger equal to or greater than 2), to provide an arrangement such that(N−1) turn portion of the selected coil is in mesh with the selectedcoil. This can realize an array type choke coil small in size, capableof providing a high coupling and capable of coping with a large current.

In the above structure, the coil group may be arranged such that adifference between an outer diameter and an inner diameter of theselected coil and a difference between an outer diameter and an innerdiameter of the adjacent coil are equal, and a distance between a centerpoint of the selected coil and a center point of the adjacent coilcoincides with a half of the sum of the outer diameter of the selectedcoil and the inner diameter of the adjacent coil. This can realize anarray type choke coil small in size, capable of providing a highcoupling and capable of coping with a large current.

In the above structure, the structure may be such that a predeterminedinductance value is obtained by changing a distance between a centerpoint of at least one coil selected from the coil group and a centerpoint of a coil adjacent to the selected coil. This can set apredetermined inductance value more freely because different inductancevalues can be obtained even if the coils are equal in the number ofturns.

In the above structure, the coil group may be arranged such that adirection of a magnetic flux in a coil upon flow of a current to atleast one coil selected from the coil group and a direction of amagnetic flux upon flow of a current to a coil adjacent the selectedcoil are same in direction. This can provide an excellent direct-currentsuperimposition characteristic and a small-sized, short structure.

In the above structure, the coil group is arranged such that a directionof a magnetic flux in a coil upon flow of a current to at least one coilselected from the coil group and a direction of a magnetic flux uponflow of a current to a coil adjacent the selected coil are different.This can further increase the inductance value while keeping asmall-sized form.

In the above structure, the coil group may be arranged with theplurality of coils all in line. This can control the inductance valuewith high accuracy.

In the above-explained array type choke coil, the structure may be suchthat at least one coil selected from the plurality of coils is arrangedin a position deviated from a plurality of other coils arranged in line.This can further size-reduce the array type choke coil entire formbecause a plurality of coils can be efficiently charged and arrangedwithin a magnetic material.

In the above-explained array type choke coil, the coil group may bearranged such that at least one of selected two or more input terminalsand output terminals is arranged on the same surface in an exposedmanner. This can facilitate circuit arrangement with a semiconductorintegrated circuit or the like, making it easy to carry out array typechoke coil mounting and operation of confirming the same.

In the above-explained array type choke coil, the structure may be suchthat the coil group has a plurality of coils constituting the coil groupburied within the magnetic material in a longitudinal direction. Thisstructure can provide the operation region in a high-frequency regionand reduce inductance value and direct-current resistance value.Moreover, it is possible to realize an array type choke coil capable ofcoping with a large current and of being reduced in size.

In the above structure, a predetermined inductance value may be obtainedby changing an interval of the plurality of coils. This can easilyrealize a desired inductance value because inductance value can bechanged even with the same number of turns.

In the above structure, the coil group may be arranged such thatmagnetic fluxes in the coils caused upon flowing currents to theplurality of coils are in the same direction. This can reduce ripplecurrents.

In the above structure, the coil group may be arranged such thatmagnetic fluxes in the coils caused upon flowing currents to theplurality of coils alternate in direction. This can improve thedirect-current superimposition characteristic.

In the above structure, the plurality of coils may have the number ofturns of (N+0.5) turns (where N is an integer equal to or greater than1), to provide an arrangement structure in that coils in upper and lowerpositions have respective 0.5 turn portions lying on the same plane.This can reduce the overall height.

In the above structure, at least one of all of input terminals andoutput terminals of the plurality of coils may be exposed in a samesurface. This can improve mountability.

In the above array type choke coil, the magnetic material may be formedat least one selected from the group consisting of a ferrite magneticmaterial, a composite of a ferrite magnetic powder and an insulatingresin and a composite of a metal magnetic powder and an insulatingresin. This can reduce short circuit occurrences and realize an arraytype choke coil capable of coping with high-frequency band because thecoil group is buried within an insulating magnetic material.

In the above array type choke coil, an insulation film may be formed onthe surface of the coil. Due to this, even in case a metal sheetstructuring the coil is bent and closely contacted, there is nopossibility to cause short circuit between metal sheets, making possibleto increase area occupation ratio.

In the above array type choke coil, the coil group may be structuredhaving at least two terminals exposed from respective differentsurfaces. This can improve heat dissipation property because theterminal can be taken broad in width. Furthermore, reliability can beimproved because connection strength can be increased at terminalregion.

In the above array type choke coil, the coil group may be structuredhaving at least one terminal exposed at least two surfaces: a bottomsurface and the surrounding surface thereof. This can improve mountingdensity and reliability.

In the above array type choke coil, the coil group may have a terminalportion exposed at least in a surface, the terminal portion beingconstituted of an underlying layer formed of nickel (Ni) or a nickel(Ni) containing layer, and an uppermost layer formed of a solder layeror thin (Sn) layer. Due to this, soldering can be done positively andreliably.

In the above array type choke coil, the magnetic material may beprovided with an indication area indicative of at least one of inputterminal and output terminal. This facilitates mounting operation andinspection before/after mounting.

In the above array type choke coil, the magnetic material may be formedin a rectangular prism form. This can facilitate automated mounting.

Meanwhile, by mounting the array type choke coil on a power supplyapparatus, it is possible to realize a power supply apparatus capable ofbeing reduced in size and operating on large current. Thus, variouselectronic apparatus can be reduced in size and thickness.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a projection perspective view of an array type choke coilaccording to embodiment 1 of the present invention.

FIG. 2 is a wiring diagram of the array type choke coil according to thesame embodiment.

FIG. 3 is a plan view showing a form of a blanked sheet before beingmade into a terminal-integrated type coil to be used in the array typechoke coil according to the same embodiment.

FIG. 4 is a perspective view of the terminal-integrated type coil to beused in the array type choke coil according to the same embodiment.

FIG. 5 is a sectional view along the line A1-A1 shown in FIG. 1 of thearray type choke coil according to the same embodiment.

FIG. 6 is a circuit diagram of a multi-phase-schemed power supplycircuit using the array type choke coil according to the sameembodiment.

FIG. 7 is a projection perspective view of an array type choke coilaccording to embodiment 2 of the present invention.

FIG. 8 is a wiring diagram of the array type choke coil according to thesame embodiment.

FIG. 9 is a sectional view along the line B1-B1 shown in FIG. 7 of thearray type choke coil according to the same embodiment.

FIG. 10 is a sectional view along the line B1-B1 shown in FIG. 7 of thearray type choke coil according to the same embodiment.

FIG. 11 is a figure showing a basic structure for determining arelationship between the distance between center points or height of thecoils and an inductance, which is a perspective view of a coil part ofterminal-integrated type coil and the surrounding magnetic materialregion.

FIG. 12A is a projection perspective view showing an array type chokecoil arrangement structure for determining respective relationshipbetween the distances between center points or heights of the coils andinductances, in the array type choke coil according to the sameembodiment.

FIG. 12B is a sectional view showing an array type choke coilarrangement structure for determining respective relationship betweendistances between the center points or heights of the coils andinductances, in the array type choke coil according to the sameembodiment.

FIG. 13A is a figure showing a relationship between the distance betweencenter points of the coils and an inductance, in the array type chokecoil according to the same embodiment.

FIG. 13B is a figure showing a relationship between the height of centerpoints of the coils and an inductance, in the array type choke coilaccording to the same embodiment.

FIG. 14 is a figure showing a modification of the array type choke coilaccording to the same embodiment, which is a perspective view showing astructure arranging another terminal-integrated type coil in a positiondeviated from a plurality of terminal-integrated type coils arranged inline.

FIG. 15 is a projection perspective view of an array type choke coilaccording to embodiment 3 of the present invention.

FIG. 16 is a sectional view along the line B2-B2 shown in FIG. 15 of thearray type choke coil according to the same embodiment.

FIG. 17A is a projection perspective view in the case of a positivecoupled structure, in an array type choke coil according to embodiment 4of the present invention.

FIG. 17B is a wiring diagram of an array type choke coil in a positivecoupled structure according to the same embodiment.

FIG. 18 is a sectional view along the line A2-A2 shown in FIG. 17A ofthe array type choke coil according to the same embodiment.

FIG. 19A is a sectional view along the line B3-B3 shown in FIG. 17A ofthe array type choke coil according to the same embodiment.

FIG. 19B is a sectional view along the line B3-B3 shown in FIG. 17A ofthe array type choke coil according to the same embodiment.

FIG. 20A is a projection perspective view in the case of a negativecoupled structure, in the array type choke coil according to the sameembodiment.

FIG. 20B is a wiring diagram of the array type choke coil in a negativecoupled structure according to the same embodiment.

FIG. 21A is a sectional view of the array type choke coil according tothe same embodiment, the structure of which is such that the magneticfluxes extending through two coils are the same in direction.

FIG. 21B is a sectional view of the array type choke coil according tothe same embodiment, the structure of which is such that the magneticfluxes extending through two coils are the same in direction.

FIG. 22A is a figure showing a basic structure for determining arelationship between the distance between center points of the coils andan inductance in the array type choke coil according to the sameembodiment, which is a perspective view of a coil part ofterminal-integrated type coil and the surrounding magnetic materialregion.

FIG. 22B is a projection perspective view showing an array type chokecoil arrangement structure for determining a relationship between thedistance between center points the coils and inductances, in the arraytype choke coil according to the same embodiment.

FIG. 22C is a plan view showing an array type choke coil arrangementstructure for determining a relationship between the distance betweencenter points the coils and inductances, in the array type choke coilaccording to the same embodiment.

FIG. 22D is a view showing a relationship between the distance betweencenter points the coils and an inductance, in the array type choke coilaccording to the same embodiment.

FIG. 23A is a modification of the array type choke coil according to thesame embodiment, which is a projection perspective view showing the casein which a three-array type choke coil is in a positive coupledstructure.

FIG. 23B is a wiring diagram of the three-array type choke coil in apositive coupled structure of the same modification.

FIG. 23C is an another modification of the array type choke coilaccording to the same embodiment, which is a projection perspective viewshowing the case in which a three-array type choke coil is in a negativecoupled structure.

FIG. 23D is a wiring diagram of a three-array type choke coil in anegative coupled structure of the same modification.

FIG. 24A is still another modification of the array type choke coilaccording to the same embodiment, in a projection perspective view of anarray type choke coil arranging terminal-integrated type coils in aV-form on the same plane into a negative coupled structure.

FIG. 24B is a side view of the array type choke coil of this othermodification.

FIG. 24C is a wiring diagram of the array type choke coil of this othermodification.

FIG. 25 is yet another modification of the array type choke coilaccording to the same embodiment, in a sectional view of an array typechoke coil arranging the center points of terminal-integrated type coilson a line.

FIG. 26 is a projection perspective view of the array type choke coilaccording to embodiment 5 of the present invention.

FIG. 27 is the array type choke coil according to the same embodiment,in a plan view showing a form of a blanked plate for fabricating aterminal-integrated type coil.

FIG. 28 is the array type choke coil according to the same embodiment,in a perspective view showing a form bent into a terminal-integratedtype coil.

FIG. 29 is a sectional view along the line A3-A3 shown in FIG. 26 of thearray type choke coil according to the same embodiment.

FIG. 30 is a sectional view along the line B4-B4 shown in FIG. 26 of thearray type choke coil according to the same embodiment, which is a viewshowing the case of a positive coupled structure.

FIG. 31 is a sectional view along the line B4-B4 shown in FIG. 26 of thearray type choke coil according to the same embodiment, which is a viewin the case of a negative coupled structure.

FIG. 32A is a view for explaining a relationship between a distancebetween coil center points and a coupling in the array type choke coilaccording to the same embodiment, which is a sectional view of the arraytype choke coil in a structure with a distance between center points R=6mm.

FIG. 32B is the array type choke coil according to the same embodiment,in a sectional view of the array type choke coil in a structure with adistance between center points R=7 mm.

FIG. 32C is the array type choke coil according to the same embodiment,in a sectional view of the array type choke coil in a structure with adistance between center points R=8 mm.

FIG. 32D is the array type choke coil according to the same embodiment,in a sectional view of the array type choke coil in a structure with adistance between center points R=0 mm.

FIG. 33A is a sectional view showing a coil part structure of an arraytype choke coil according to embodiment 6 of the present invention.

FIG. 33B is the array type choke coil according to the same embodiment,in a sectional view showing similarly a coil part structure.

FIG. 34 is the array type choke coil according to the same embodiment,in a figure showing a relationship between the distance between coilcenter points S and an inductance.

FIG. 35 is a sectional view of an array type choke coil in amodification of the array type choke coil according to the sameembodiment.

FIG. 36A is a projection perspective view of an array type choke coil inanother modification of the array type choke coil according to the sameembodiment.

FIG. 36B is a perspective view of a terminal-integrated type coil to beused in the array type choke coil according to the another modification.

FIG. 36C is a perspective view of a terminal-integrated type coil to beused in the array type choke coil according to the another modification.

FIG. 36D is a wiring diagram of the array type choke coil of the anothermodification.

FIG. 37A is a projection perspective view of an array type choke coil instill another modification of the array type choke coil according to thesame embodiment.

FIG. 37B is a perspective view of a terminal-integrated type coil to beused in the array type choke coil according to the still anothermodification.

FIG. 37C is a perspective view of a terminal-integrated type coil to beused in the array type choke coil according to the still anothermodification.

FIG. 37D is a wiring diagram of the array type choke coil of the stillanother modification.

FIG. 38A is a projection perspective view of an array type choke coil inyet another modification of the array type choke coil according to thesame embodiment.

FIG. 38B is a perspective view of a terminal-integrated type coil to beused in the array type choke coil according to the yet anothermodification.

FIG. 38C is a perspective view of a terminal-integrated type coil to beused in the array type choke coil according to the yet anothermodification.

FIG. 38D is a wiring diagram of the array type choke coil of the yetanother modification.

FIG. 39 is an exterior perspective view of an array type choke coilaccording to embodiment 7 of the present invention.

FIG. 40 is an exterior perspective view showing another structure of anarray type choke coil according to embodiment 7 of the presentinvention.

FIG. 41 is an exterior perspective view showing still another structureof an array type choke coil according to embodiment 7 of the presentinvention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereunder, embodiments of the present invention will be explained indetail while referring to the drawings. Note that, in the ensuingdrawings, like structural elements are attached with like references andhence omitted of explanations thereof.

EMBODIMENT 1

FIG. 1 is a projection perspective view of an array type choke coil inembodiment 1 of the present invention. FIG. 2 is a wiring diagram of thearray type choke coil. First coil 1 is structured by being integrallyformed with input terminal 2 and first output terminal 3. Second coil 4is also structured by being integrally formed with second input terminal5 and second output terminal 6. First coil 1 and second coil 4 are woundin the same direction, both of which have the number of turns of 1.5turns. Due to this, in the case of flow of a current from first inputterminal 2 of first coil 1 and second input terminal 5 of second coil 4,first coil 1 and second coil 4 have in-coil magnetic fluxes assuming inthe same direction.

There is provided an arrangement such that an axis of first coil 1 andan axis of second coil 4 are in parallel and wherein first coil 1 is inthe upper position while second coil 4 is in the lower position.Incidentally, the respective axes refer to axes passing the center ofthe ring-formed coil. Because first coil 1 and second coil 4 have thesame number of turns, whose center points are also different in height.

First coil 1 and second coil 4 are buried within magnetic material 7.Magnetic material 7 in the entire is formed nearly a rectangular prismform. Accordingly, the array type choke coil of the present embodiment,because nearly in a rectangular prism form in the entire, is easy tohandle during automated mounting. Mistaken chucking or the like lessoccurs during mounting.

FIG. 3 and FIG. 4 are views for explaining a fabrication method andstructure of first coil 1 and second coil 4. FIG. 3 is a plan view of ablanked sheet. FIG. 4 is a perspective view showing a state in that thesame is folded and fabricated into a terminal-integrated type coil,i.e., first coil 1 and second coil 4.

Here, first coil 1 and second coil 4 is explained in concrete structureby use of FIGS. 3 and 4. First of all, explanation is made on afabrication method and structure of a terminal-integrated type coil thatis to be made into first coil 1 and second coil 4. FIG. 3 is a plan viewshowing a form of a blanked sheet before being formed into aterminal-integrated type coil. The blanked plate comprises three arcuateparts 31 in a ring form formed by etching or blanking a metal sheet,connections 33 joining between the arcuate parts 31 and two ends 32extended from the two arcuate parts. As a metal plate is mainly used amaterial, such as copper or silver, low in electric resistance but greatin thermal conductivity. The blanked sheet is not limited to the formingmethod based on etching or blanking, but may be formed by a workingmethod of cutting, press-working or the like.

Insulation film 51 is formed over a surface of three arcuate parts 31.This insulation film 51 can be easily formed if applying an insulatingresin, e.g., polyimide. This prevents short circuit between the coilswhen arcuate parts 31 are folded and vertically superimposed to formcoil part 34. Because insulation film 51 is not provided on connection33, there is no occurrence of breakage or stripping of insulation film51 even if connection 33 is bent, thus preventing characteristicdeterioration resulting from insulation film 51.

Three arcuate parts 31 of the blanked plate are bent at connection 33such that the center points are overlapped one with another as shown inFIG. 4, thus being made into coil part 34. By bending arcuate parts 31,two ends 32 are provided radial about a center of coil part 34, thusforming a terminal-integrated coil.

Due to this, first coil 1 and second coil 4 realize a coil structure inthat insulation treatment is done by insulation film 51 in coil parts34. Accordingly, superposition is possible without providing any gapbetween the respective coils or between arcuate parts 31. As a result,an array type choke coil is to be realized great in area occupationratio.

Next, magnetic material 7 can use a composite magnetic material inwhich, for example, a soft magnetic alloy powder is added with asilicone resin by 3.3 weight part and mixed together followed by beingpassed through a mesh into a regulated-particle powder. The compositemagnetic material like this has a structure in that the particle of thesoft magnetic alloy powder is covered by silicone resin. The softmagnetic alloy powder can use a soft magnetic alloy powder in a ratio ofiron (Fe)—nickel (Ni) of 50:50 having a mean particle size of 13 μmprepared by, for example, water atomization method.

The magnetic material 7 for the array type choke coil of this embodimentused the soft magnetic alloy powder as a metal magnetic powder and thesilicone resin as an insulation resin, thereby forming a compositethereof. However, this is not limitative. For example, it may be acomposite of a ferrite magnetic material and an insulation resin or acomposite of a metal magnetic powder other than the above and aninsulation resin. Furthermore, it may be of only a ferrite magneticmaterial instead of a composite. Although resistance is higher than thecase using a metal magnetic powder, conversely eddy currents can beprevented from occurring because of the increased resistance. Favorablecharacteristics is obtainable in the high frequency band.

It is possible to use a metal magnetic powder containing 90 weightpercentage or more in total of iron (Fe), nickel (Ni) and cobalt (Co) incomposition wherein the metal magnetic powder is at a filling ratio of65 volume percentage to 90 volume percentage. The use of such a magneticpowder can obtain magnetic material 7 formed of a composite high insaturation magnetic flux density and in magnetic permeability. The metalmagnetic powder having a mean particle size of 1 μm-100 μm is effectivein reducing eddy currents.

Magnetic material 7 excellent in insulation can prevent short circuitbetween a plurality of coils or coil parts 34, enabling to realizehighly reliable array type choke coil. Meanwhile, because the use ofsuch magnetic material 7 can suppress an eddy current from occurring inmagnetic material 7 due to flow of a current to the array type chokecoil, it is possible to realize an array type choke coil capable ofcoping with high-frequency band. Furthermore, where a power circuitapparatus or the like is configured by use of the array type choke coil,insulation from other components, etc. can be kept.

FIG. 5 shows a sectional view along the line A1-A1 in the array typechoke coil shown in FIG. 1. Explanation is made on a method ofmanufacturing an array type choke coil shown in FIGS. 1 and 5 by the useof terminal-integrated type coils and magnetic material 7. At first,magnetic material 7 is placed in a metal die, to arrange twoterminal-integrated type coils in a positional relationship setrespectively. Thereafter, magnetic material 7 furthermore is placed in ametal die, followed by carrying out pressing. The pressure upon pressingis applied at 3 tons/cm², for example. After removal out of the metaldie, heating process is conducted at 150° C. for about 1 hour, beingallowed to cure. Thereafter, respective ends 32 are bent along the sidesurface of magnetic material 7 to the bottom, to thereby form firstinput terminal 2, second input terminal 5, first output terminal 3 andsecond output terminal 6.

Underlying layer 52 is formed on first input terminal 2, first outputterminal 3, second input terminal 5 and second output terminal 6, in apart exposed out of the surface of magnetic material 7. Uppermost layer53 is formed in a manner so as to cover underlying layer 52. Underlyinglayer 52 is preferably a nickel (Ni) layer, and uppermost layer 53 ispreferably a solder layer or thin (Sn) layer. Incidentally, insulationfilm 51 is formed on the surface of coil part 34 buried in magneticmaterial 7.

As in the above, the solder layer as uppermost layer 52 is formed overthe terminal exposed out of the surface of the array type choke coil,including the bottom thereof. This enables the array type choke coil tobe positively mounted by means of a board or the like. Meanwhile,because the terminals are bent not to the side surface but to theunderside of the array type choke coil, it is possible to reduce themounting occupation area in mounting the array type choke coil onto aboard or the like. Furthermore, because the terminal is formed with theNi layer as underlying layer 52 and the solder layer as uppermost layer53 in the present embodiment, it is possible to prevent the Ni layerfrom oxidizing and make solderability favorable.

In the case of an array type choke coil in the conventional structurefor example, when it is used in an insufficient state of mounting of oneterminal of the choke coil on the board or the like, there encounters acase in which the terminal is detached from the board or the like byheat generation or a case of occurrence of a phenomenon in which thearray type choke coil is inverted from the board or the like. However,in the case of the array type choke coil of the present embodiment,because a terminal region excellent in solderability is formed over fromthe side surface to the bottom, such a trouble can be positivelyprevented from occurring.

Because first coil 1 and second coil 4 are structured by blanking andbending a metal sheet, even if used in a high frequency band, smallerdirect-current resistance value and sufficient inductance value can beheld and large current can be flowed as compared to the coil structuredby winding a conductor wire. Meanwhile, because a sufficient inductancevalue can be secured without increasing the number of coil turns, it ispossible to realize a small, short structured array type choke coil.

First coil 1 and second coil 4 are buried within magnetic material 7.Magnetic material 7 is excellent in insulatability. Accordingly, it ispossible to prevent a trouble occurrence such as short circuit betweenthe plurality of coils or coil parts 34. Particularly, by using amaterial containing at least one or more of iron (Fe), nickel (Ni) andcobalt (Co) as a main component of the metal magnetic powder formagnetic material 7, magnetic material 7 can be obtained that has amagnetic characteristic satisfying a high saturation magnetic fluxdensity and high permeability capable of coping with a large current,thus realizing an array type choke coil having a great inductance value.

Hereunder, the operation of the gang choke coil of this embodiment isexplained in the following. First coil 1 and second coil 4 are givenequal in the number of turns and the same in the winding direction.Although a magnetic field is caused if flowing a current from firstinput terminal 2 and second input terminal 5, the magnetic fluxesextending through the respective coils are in the same direction. Firstcoil 1 and second coil 4 are arranged to be staggered to provide amagnetic coupling.

A magnetic flux is caused by flow of a current to first coil 1. Themagnetic flux constitutes a magnetic circuit extending through anin-coil center of first coil 1, to pass an outside of first coil 1 andreturn again to the in-coil center of first coil 1. When flowing acurrent to second coil 4, the magnetic flux similarly constitutes amagnetic circuit extending through an in-coil center of second coil 4,to pass an outside of second coil 4 and return again to the in-coilcenter of second coil 4. Because first coil 1 and second coil 4 arearranged to be staggered at this time, there is a magnetic fluxsuperimposed over a magnetic flux of a magnetic circuit caused by flowof a current to second coil 4, of the magnetic flux of a magneticcircuit caused by flow of a current to first coil 1. Meanwhile, whenflowing a current to second coil 4, there is similarly a magnetic fluxsuperimposed over the magnetic flux of a magnetic circuit caused by flowof a current to first coil 1, of the magnetic flux of the magneticcircuit.

Due to this, coupling takes place between first coil 1 and second coil4. Because first coil 1 and second coil 4 are arranged to be staggered,further increased is the superimposition of the magnetic flux of themagnetic circuit caused by first coil 1 and the magnetic flux of themagnetic circuit caused by second coil 4, thus realizing a highcoupling.

In the case of an array type choke coil, the inductance value isinfluenced by a coupling of first coil 1 and second coil 4. The couplingof first coil 1 and second coil 4 changes depending upon asuperimposition degree of a magnetic flux of a magnetic circuit causedby flow of a current to first coil 1 and a magnetic flux of a magneticcircuit caused by flow of a current to second coil 4. Thissuperimposition changes depending upon an arrangement of first coil 1and second coil 4. Consequently, in case the distance is changed betweena center point of first coil 1 and a center point of second coil 4, achange is also caused in the superimposition of the magnetic fluxes.Therefore, the inductance value of the array type choke coil can bechanged without changing the number of turns of first coil 1 and secondcoil 4. Namely, by suitably changing the distance between the centerpoint of first coil 1 and the center point of second coil 4, apredetermined inductance value can be easily obtained.

Similarly, by changing the height of the center point of first coil 1and the center point of second coil 4, a change is similarly caused inthe superimposition of the magnetic fluxes. Accordingly, by this method,the inductance value of the array type choke coil can be also changedwithout changing the number of turns of first coil 1 and second coil 4.Particularly, if the coil height is changed, it is possible to readilyrealize more small-sized short structure.

As described above, the array type choke coil of the present embodimentcan realize an array type choke coil small in size, capable of providinga high coupling and capable of coping with large current. Particularly,the array type choke coil of the present embodiment is preferably usedin a power supply circuit having an arrangement in which a plurality ofDC/DC converters are connected in parallel, as shown in its circuitdiagram in FIG. 6.

FIG. 6 shows a circuit diagram of a power supply circuit using amulti-phase scheme. Input power 61 is inputted to switching element 62,wherein choke coil 63 and capacitor 64 constitute an integrationcircuit, to connect load 65 at its output. Incidentally, 500 kHz forexample is used as a switching frequency. The power supply circuit shownin FIG. 6 can realize frequency and current increase with efficiency byplacing the plurality of DC/DC converters under phase control forparallel operation. However, in the conventional structure, there is acase to cause a ripple current as an output. In order to obtain atargeted direct current as an output, such ripple current is preferablyas small as possible. For ripple current reduction, it is effective toincrease the inductance value of choke coil 63.

Meanwhile, in order to provide a power supply circuit coping with largecurrent, there is a need to prevent the magnetic flux of choke coil 63from saturating when a large current flows. In order for this, theinductance value of choke coil 63 is preferably small. In case theinductance value is decreased, the direct-current superimpositioncharacteristic of choke coil 63 can be enhanced thus making it possibleto cope with greater current. Meanwhile, the above power supply circuitis assumably mounted on an electronic apparatus, e.g., a notebookpersonal computer, choke coil 63 is required small in size.

For this reason, the array type choke coil of the present embodiment isused as choke coil 63 for the power supply circuit shown in FIG. 6, useis possible in a high frequency band and wherein current increase can berealized with efficiency. The array type choke coil of this embodiment,because of capability of obtaining a predetermined inductance value bychanging the center-point distance and height of each coil, is allowedto freely cope with the case to suppress ripple currents, the case tocope with a large current, etc.

Although the array type choke coil of the present embodiment had twoterminal-integrated type coils in the gang, those may be three, four ormore in the number. Those terminal-integrated type coils may be arrangedin line. Alternatively, the terminal-integrated type coils arranged inline may be arranged in two rows, three rows or more on a plane, orotherwise may be in a stack arrangement. The number of turns is notlimited to 1.5 turns. Furthermore, there is no especial need to providethe coils the same in the number and winding direction.

As in the above, the array type choke coil of the present embodiment canrealize an array type choke coil that is small in size, capable ofproviding a high coupling and capable of coping with a large current,hence being effective where the array type choke coil is mounted on anelectronic apparatus such as a cellular telephone.

EMBODIMENT 2

While referring to FIGS. 7 to 10, explanation is made on an array typechoke coil in embodiment 2 of the present invention. The array typechoke coil of the present embodiment is similar in basic structure tothe array type choke coil in embodiment 1 of the present invention.However, the present embodiment is characterized in that a V-formedarrangement is provided by increasing by one the terminal-integratedtype coils.

FIG. 7 is a projection perspective view of an array type choke coil inthe present embodiment. FIG. 8 is a wiring diagram of this array typechoke coil. First coil 71 is formed integrally with first input terminal72 and first output terminal 73. Second coil 74 is similarly formedintegrally with second input terminal 75 and second output terminal 76.Meanwhile, third coil 77 is formed integrally with third input terminal78 and third output terminal 79. The respective coils are wound in thesame direction, all of which have the number of turns of 1.5 turns. Dueto this, in the case of flowing currents to first coil 71, second coil74 and third coil 77 through the respective input terminals, themagnetic fluxes extend through first coil 71, second coil 74 and thirdcoil 77 are the same in direction.

Meanwhile, there is provided an arrangement such that the center axis offirst coil 71, the center axis of second coil 74 and the center axis ofthird coil 74 are in parallel and wherein first coil 71 and third coil77 are positioned in the upper stand while second coil 74 is positionedin the lower stand. This places first coil 71, second coil 74 and thirdcoil 77 in a V-formed arrangement. First coil 71, second coil 74 andthird coil 77 are buried within a magnetic material 7. The magneticmaterial 7 is formed to assume a rectangular prism. First coil 71,second coil 74 and third coil 77 are terminal-integrated type coilsformed by blanking and folding a metal sheet similarly to theterminal-integrated type coils used in the array type choke coil inembodiment 1 of the present invention. The manufacturing method is thesame and hence omitted of explanation.

FIGS. 9 and 10 are sectional views along the line B1-B1 in the arraytype choke coil of the present embodiment shown in FIG. 7. Note thatthese figures are structurally the same but arrows C1, C2 C3 shown inFIG. 9 and arrows D1, D2, D3 shown in FIG. 10 are different in directionin part thereof. These arrows C1, C2, C3, D1, D2, D3 represent thedirections of the magnetic fluxes extending through first coil 71,second coil 74 and third coil 77.

In the case of FIG. 9, there are shown the directions of magnetic fluxeswhen currents are inputted to first coil 71 and third coil 77respectively through first input terminal 72 and third input terminal 78while to second coil 74 through second output terminal 76. Accordingly,opposite are the direction of the magnetic flux extending through thecoils of first coil 71 and third coil 77 and the direction of themagnetic flux extending through the coils of second coil 74. This stateis referred to as positive coupling.

Meanwhile, in the case of FIG. 10, there are shown the directions ofmagnetic fluxes when currents are inputted to first coil 71, second coil74 and third coil 77 respectively through first input terminal 72,second input terminal 75 and third input terminal 78. Accordingly, themagnetic fluxes extending respectively through the coils of first coil71, second coil 74 and third coil 77 are the same in direction. Thisstate is referred to as negative coupling.

The gang choke coil of the above structure is explained of its operationin the below.

In FIG. 9, in case of flowing a current to first coil 71, a magneticflux takes place. The magnetic flux constitutes a magnetic circuit in amanner so as to extend through an in-coil center of first coil 71, topass an outside of first coil 71 and return again to the in-coil centerof first coil 71. When currents flow to second coil 74 and third coil77, a magnetic circuit is similarly constituted. At this time, becausefirst coil 71, second coil 74 and third coil 77 are in a V-formedarrangement, there exists a superimposed magnetic flux among themagnetic fluxes of magnetic circuits caused by flow of currents to firstcoil 71, second coil 74 and third coil 77. Particularly, the magneticflux superimpositions are intensified respectively around the centers ofthe coils.

Namely, of the magnetic flux caused by flow of a current to first coil71, there is a magnetic flux extending through an in-coil center ofsecond coil 74. Likewise, of the magnetic flux caused by flowing acurrent to third coil 77, there is a magnetic flux extending through anin-coil center of second coil 77. Because the same are the direction ofthe magnetic flux extending through the in-coil center of second coil 74and the direction of the magnetic flux extending through the in-coilcenter of second coil 74 upon flowing a current to second coil 74, thereis an increase in the magnetic flux extending through the center ofsecond coil 74.

Meanwhile, of the magnetic flux caused by flowing a current to secondcoil 74, there are magnetic fluxes extending through in-coil centers offirst coil 71 and third coil 77. Because the same are the direction ofthe magnetic fluxes extending through the in-coil centers of first coil71 and third coil 77 and the direction of the magnetic fluxes extendingthrough the in-coil center of first coil 71 and through the in-coilcenter of third coil 77 upon flowing currents to first coil 71 and thirdcoil 77, there is an increase in the magnetic fluxes extending throughthe in-coil center of first coil 71 and through the in-coil center ofthird coil 77.

This causes a great magnetic field through the array type choke coil,thereby increasing the inductance value furthermore. Accordingly, incase this positive-coupled array type choke coil is used as a powersupply circuit choke coil 63 shown in FIG. 6, ripple currents can besuppressed by a great inductance value of the positive-coupled arraytype choke coil, thus realizing a power supply circuit usable in highfrequency band and capable of coping with a large current.

In the case of a structure shown in FIG. 10, when current flows to firstcoil 71, a magnetic flux takes place. The magnetic flux constitutes amagnetic circuit in a manner so as to extend through an in-coil centerof first coil 71, to pass an outside of first coil 71 and return againto the in-coil center of first coil 71. When currents flow to secondcoil 74 and third coil 77, magnetic circuits are similarly constituted.At this time, because first coil 71, second coil 74 and third coil 77are in a V-formed arrangement, there exists a superimposed magnetic fluxamong the magnetic fluxes of magnetic circuits caused by flow ofcurrents to first coil 71, second coil 74 and third coil 77.Particularly, the magnetic superimpositions are intensified respectivelyaround the centers of the coils.

Of the magnetic flux caused by flow of a current to first coil 71, thereis a magnetic flux extending through an in-coil center of second coil74. Likewise, of the magnetic flux caused by flowing a current to thirdcoil 77, there is a magnetic flux extending through an in-coil center ofsecond coil 74. Because opposite are the direction of the magnetic fluxextending through the in-coil center of second coil 74 and the directionof the magnetic flux extending through the in-coil center of second coil74 upon flowing a current to second coil 74, there is a decrease in themagnetic flux extending through the center of second coil 74.

Meanwhile, of the magnetic flux caused by flow of a current to secondcoil 74, there are magnetic fluxes extending through in-coil centers offirst coil 71 and third coil 77. Because different are the direction ofthe magnetic fluxes extending through the in-coil centers of first coil71 and third coil 77 and the direction of the magnetic fluxes extendingthrough the in-coil center of first coil 71 and through the in-coilcenter of third coil 77 upon flowing currents to first coil 71 and thirdcoil 77, there is a decrease in the magnetic fluxes extending throughthe in-coil center of first coil 71 and through the in-coil center ofthird coil 77.

This results in a decreased magnetic field caused on the array typechoke coil, thereby enabling to decrease the inductance value.Accordingly, in case of that such a negative-coupled array type chokecoil is used as power supply circuit choke coil 63 shown in FIG. 6,choke coil 63 can be enhanced in direct-current superimpositioncharacteristic because of a decreased inductance value, thus realizing apower supply circuit capable of coping with a larger current.

The inductance value of the array type choke coil in the presentembodiment is influenced by a coupling of first coil 71, second coil 74and third coil 77. Namely, the coupling of first coil 71, second coil 74and third coil 77 changes depending upon a superimposition degree of amagnetic-circuit magnetic flux caused by flow of currents to first coil71, second coil 74 and third coil 77. The superimposition changesdepending upon an arrangement of first coil 71, second coil 74 and thirdcoil 77. Accordingly, by respectively changing the distances to thecenters of first coil 71 and to third coil 77, that are coils on theboth sides of second coil 74, with reference to second coil 74, thesuperimposition of magnetic flux can be varied. By a change of magneticflux superimposition, the inductance value of the array type choke coilcan be changed without changing the number of turns of first coil 71,second coil 74 and third coil 77.

Here, there is shown, in FIGS. 11 to 13B, a result of determining arelationship between a distance to, or height of, a center point offirst coil 71 and a center point of second coil 74 and an inductancevalue of the array type choke coil in the present embodiment in positiveor negative coupling.

FIG. 11 is a projection perspective view showing, by extraction, aregion of the coil part 34 and the surrounding magnetic material 7 ofthe terminal-integrated type coil used in the present embodiment. Thecore as magnetic material 7 is a rectangular prism of 10 mm in thevertical by 10 mm in the horizontal by 3.5 mm in the height. Coil part34 of the terminal-integrated type coil is given an inner diameter 4.2mm, an outer shape 7.9 mm, a height 1.7 mm and a magnetic permeabilityμ=26. Note that, although the number of turns is set to be 1.5 turns inFIGS. 7 to 10, the above relationship was determined by setting thenumber of turns as 3 turns.

FIGS. 12A and 12B are a projection perspective view (FIG. 12(A)) andsectional view (FIG. 12(B)) of an array type choke coil arrangementstructure in the case of using the coil part 34 of theterminal-integrated type coil shown in FIG. 11. Those are viewsexplaining the structures respectively for determining a relationshipbetween distances D, which are distances from second coil 74 to firstcoil 71 and to third coil 77, respectively, and an inductance value, anda relationship between heights H of first coil 71 and of third coil 77with reference to second coil 74 and an inductance value.

FIG. 13A is a result of determining inductance value L when distance Dbetween the center point of first coil 71 and the center point of secondcoil 74 (this is equal to the distance D between the center point ofthird coil 77 and the center point of second coil 74) is varied withsetting height H to be constant as H=2.7 mm. From a result of this, inthe case of positive coupled arrangement of the coils, inductance valuecan be increased as compared to the case of negative coupledarrangement. It has been known that changing distance D can varyinductance value L.

FIG. 13B is a figure showing a relationship between distance D andinductance value L in the case of changing height H with setting thedistance D to be constant. As can be understood from this figure, it hasbeen found that changing height H can vary inductance value L. Notethat, at this time, distance D was set to be constant at D=6.5 mm.

This can realizes an array type choke coil obtaining desired inductancevalue L by varying distance D and height H through changing thepositions of the center point of first coil 71 and center point of thirdcoil 77. Although the present embodiment set the distance between thecenter point of first coil 71 and the center point of second coil 74equal to the distance between the center point of third coil 77 and thecenter point of second coil 74, the present invention is not limited tothis. These distances may be different, respectively. Meanwhile,although the present embodiment set the heights of first coil 71 andthird coil 77 equal, these may be not necessarily equal but bedifferent.

From the result of these, in case an array type choke coil in anarrangement structure having a distance to a center point of first coil71 and to center point of third coil 77 with reference to second coil 74designed to increase the inductance value is used as choke circuit 63 ofa power supply circuit shown in FIG. 6 similarly to the array type chokecoil of embodiment 1, it is possible to realize a power supply circuitcapable of suppressing ripple currents and capable of coping with alarge current in a high-frequency band.

Meanwhile, in case an array type choke coil in an arrangement structurehaving a distance between a center point of first coil 71 and centerpoint of third coil 77 designed to suppress the inductance value is usedas choke coil 63 of the power supply circuit shown in FIG. 6 similarlyto the array type choke coil of embodiment 1, it is possible to realizea power supply circuit capable of enhancing the direct-currentsuperimposition characteristic of choke coil 63 and capable of copingwith a larger current.

Incidentally, although the array type choke coil of the presentembodiment had the terminal-integrated type coils three in the gang,those may be four or more in the gang thus being increased in line. Theterminal-integrated type coils arranged in line may be arranged in tworows, three rows or more on a plane, or otherwise may be in a stackarrangement. The number of coil turns is not limited to 1.5 turns.Furthermore, there is no especial need to make equal the number andwinding direction of the coils. Although the present embodiment arrangedthe coils in a V-form, they may be arranged in an inverted V-form.

As shown in FIG. 14, it is possible to arrange terminal-integrated typecoil 122 in a position deviated from a plurality of terminal-integratedtype coils 121, 121 set up in line. This can enhance the charge ratio ofthe coils within magnetic material 7, enabling to further reduce thesize of the array type choke coil overall.

As in the above, the array type choke coil of the present embodiment canrealize an array type choke coil capable of being reduced in size,providing a high coupling and capable of coping with a large current.Hence, it exhibits great effect if used on an electronic apparatus suchas a cellular telephone.

EMBODIMENT 3

While referring to FIGS. 15 and 16, explanation is made on an array typechoke coil in embodiment 3 of the present invention. The array typechoke coil of the present embodiment is similar in basic structure tothe array type choke coil in embodiment 1 of the present invention.

FIG. 15 is a projection perspective view of an array type choke coil inthe present embodiment. First coil 131, second coil 132 and third coil133 are terminal-integrated type coils formed by blanking and folding ametal sheet, similarly to the array type choke coil of the firstembodiment. The respective coils have the number of turns of 2.5 turns.

FIG. 16 is a sectional view along the line B2-B2 in the array type chokecoil shown in FIG. 15. There is provided an arrangement such that thecenter axis of first coil 131, the center axis of second coil 132 andthe center axis of third coil 133 are in parallel and wherein first coil131 and third coil 133 are positioned in the upper stand while secondcoil 132 is positioned in the lower stand. There is provided anarrangement such that end 134 of first coil, end 135 of second coil 135and end 136 of third coil are on the same plane. The coil parts of firstcoil 131, second coil 132 and third coil 133 are buried within themagnetic material 7.

The array type choke coil in the above structure is explained of itsoperation in the below.

The array type choke coil of the present embodiment can be reduced insize, provide a high coupling and cope with a large current, which issimilar to embodiment 1. The array type choke coil of the presentembodiment provides a characterization in the number of turns of coiland arrangement of the coils, thereby making it possible to realize afurther small-sized shorter structure.

As shown in FIG. 16, first coil 131 at its left part having a height of3 turns is laid over the right part of second coil 131 having a heightof 2 turns. Third coil 133 at its right part having a height of 2 turnsis laid over the left part of second coil 132 having a height of 3turns. Because first coil 131, second coil 132 and third coil 133 arerespectively given 2.5 turns, such a coil arrangement is feasible.Accordingly, when first coil 131 and third coil 133 are structurallyarranged upper while second coil lower, it is possible to easily realizea coil stack structure increased in charge degree without making auseless space. This can realize an array type choke coil further smallerin size and shorter in structure.

In case such an array type choke coil is used as a choke coil 63 of apower supply circuit shown in FIG. 6, size reduction is possible whileeasily securing an inductance value required in design, thus realizing apower supply circuit apparatus small in size and high in performance.

EMBODIMENT 4

An array type choke coil structure in embodiment 4 of the presentinvention is explained with using FIGS. 17A, 17B and 18. FIG. 17A is aprojection perspective view of the array type choke coil of the presentembodiment, and FIG. 17B is a wiring diagram thereof. FIG. 18 is asectional view along the line A2-A2 of the array type choke coil shownin FIG. 17A.

At first, because the terminal-integrated type coil 50 may be fabricatedsimilarly to the fabrication method shown in FIGS. 3 and 4 of embodiment1, explanation is omitted. The number of turns of terminal-integratedtype coil 50 does not always have to be an integer but can be setfreely, e.g., 1.5 turns or 1.75 turns. This is true for coil size,inductance value and the like. The present embodiment explains thosecoils merely as terminal-integrated type coil 50 in the below.Accordingly, the terminals connected to them are explained merely asinput terminal 20 and output terminal 30. Magnetic material 7, becausethe same one as the material explained in embodiment 1 can be fabricatedin the same manufacturing method, is omitted of explanation.

The array type choke coil of the present embodiment is structured byarranging a plurality of terminal-integrated type coils 50 withinmagnetic material 7. For an array type choke coil, terminal-integratedtype coils 50 are first respectively arranged in predeterminedpositional relationship, and press-formed by covering the part exceptingends with magnetic material 7. The condition of press-forming issatisfactorily done similarly to embodiment 1, and hence omitted ofexplanation.

The ends extended from magnetic material 7 are exposed at and bent onthe outer layer, and the exposed region is formed with underlying layer52 of nickel (Ni) or an alloy containing nickel (Ni) in order to preventthe terminals of copper or silver from oxidizing and to improveconnection reliability of solder or the like. Furthermore, an uppermostlayer 53 of solder, thin (Sn) or lead (Pb) is formed on the underlyinglayer 52 of Ni or an alloy containing Ni.

All the exposed ends are bent along the bottom and the surface adjacentto the bottom of the array type choke coil, and formed into inputterminal 20 and output terminal 30. This provides substantially aleadless structure, enabling high density mounting as compared to theconventional array type choke coil with leads. The above manufacturingmethod is basically the same as embodiment 1.

Incidentally, magnetic material 7 is preferably in a rectangular prismform, which is similar to the case of embodiment 1. This facilitatessucking for automated bonding, alignment onto a printed board, and thelike. Mounting direction and terminal polarity may be shown, and chamfermay be performed. Furthermore, there is no especial restriction on theform of the magnetic material provided that the top surface thereof isin a planer form and polygonal or circular cylindrical form will do.

Explanation is made below on the arrangement structure of a plurality ofcoils to be buried within magnetic material 7. The present embodimentarranges two coils same in coil size and the number of turns on a sameplane as shown in FIG. 17A such that the magnetic fluxes to be generatedat respective coil centers are to be caused in opposite directions. FIG.17B is a wiring diagram thereof, wherein power-supply connection pointsI1, I2, O1, O2 are shown at input terminals 20 and output terminals 30of the respective terminal-integrated type coils 50, 50.

Explanation is made concerning what form a magnetic field to occurbecomes in the case of providing the above structure. FIGS. 19A and 19Bare sectional views along the line B3-B3 shown in FIG. 17A wherein, whena current flows, the magnetic fluxes extending through the respectivecoils become alternate in direction. Accordingly, magnetic circuits areformed to superimpose together the magnetic fluxes extending throughrespective coils. As a result, there is an increase in the inductancevalues of the respective coils. The arrangement of direction of coilsfor causing such a magnetic flux coupling is a positive couplingstructure.

Meanwhile, there is an array type choke coil structure in that two coilssame in coil size and the number of turns are arranged on the same planesimilarly to FIG. 17A but arranged such that the respective ones causemagnetic fluxes extending through the coils in the same direction whencurrent flows. FIG. 20A is a projection perspective view of array typechoke coil arranging terminal-integrated type coils 50 that are the samein the winding direction on the same plane. FIG. 20B shows a wiringdiagram of the same. Power-supply connection points I1, I2, O1, O2 arerespectively shown at input terminals 20 and output terminals 30 ofrespective terminal-integrated type coils 50, 50.

FIGS. 21A and 21B are sectional views of the array type choke coilwherein, when current flows, the magnetic fluxes extending through therespective coils are all in the same direction. Accordingly, althoughthe magnetic fluxes extending through the respective coils pass anoutside of the coil to return to the former position, the magnetic fluxcoupling in this case is weak. Magnetic circuits are respectively formedin a direction that the magnetic fluxes caused wholly on the array typechoke coil are to cancel each other. Namely, obtained is an effect tosuppress magnetic flux saturation. Namely, the arrangement structure ofcoils is negative coupling.

As described in the above, different characteristics are available inthe arrangements of positive coupling and negative coupling. Explanationis made on the result obtained by determining a relationship betweendistance R between the center points of two coils in positive couplingand inductance value L, and a relationship between distance R betweenthe center points of two coils in negative coupling arrangement andinductance value L.

FIG. 22A is a projection perspective view showing one coil part 34 and apart of magnetic material 7 surrounding the same. Coil part 34 is in asize having an inner diameter of 4.2 mm, an outer diameter of 7.9 mm anda height of 1.7 mm, the number of turns of which is set to be 3 turns.The core formed by the magnetic material 7 is provided with a magneticpermeability μ=26 and a size of 10 mm×10 mm×3.5 mm. Inductance value Lobtainable from these is L=0.595 μH.

FIGS. 22B and 22C are a projection perspective view and plan viewshowing a structure that coil part 34 and magnetic material 7 in a unitstructure shown in FIG. 22A is arranged two on a same plane. There isshown in FIG. 22D a result obtained by comparing distance R betweencenter points and inductance value L by using, as a parameter, adifference between positive coupled structure and negative coupledstructure.

When distance R between center points of two coils 50, 50 is assumed 10mm, inductance value L in a positive coupled structure was 0.579 μHwhile inductance value L in a negative coupled structure was 0.571 μHthat is −1.4% smaller than inductance value L in the positive coupledstructure. Likewise, when distance R between center points was set to be9.2 mm, inductance value L in a positive coupled structure was 0.583 μHwhile inductance value L in a negative coupled structure was 0.567 μHthat is −2.7% smaller than the same.

Namely, in a positive coupled structure, as distance R between centerpoints is decreased, inductance value L increases. Meanwhile, in anegative coupled structure, as distance R between center points isdecreased, inductance value L also decreases. Namely, in a positivecoupled structure, in case distance R between center points isdecreased, inductance value L can be increased. Without increasing thenumber of turns of the coils, a great inductance value can be obtained.Furthermore, the smaller distance R between center points is, thegreater inductance value L can be taken, which is preferred in achievingsize reduction of the array type choke coil.

Meanwhile, in a negative coupled structure, the smaller distance Rbetween center points is, inductance value L also decreases. In anegative coupled structure, because there is a mutual cancellation ofthe direct-current magnetic field components caused on the respectivecoils, the magnetic field is readily prevented from saturating even ifflowing a large current. Namely, in a negative coupled structure, byproviding a choke coil incorporating a plurality of coils, sizereduction is possible rather than the case of using a plurality of chokecoils comprising one coil in combination. Besides, direct-currentsuperimposition characteristic can be greatly improved.

Next explained is an array type choke coil arranging threeterminal-integrated type coils within magnetic material 7 (hereinafter,referred to as a three-array type choke coil).

FIG. 23A is a projection perspective view showing a structure ofarranging three terminal-integrated type coils 501, 502, 503 in line.Note that these terminal-integrated type coils, hereinafter, aredistinguishingly referred to as right coil 501, center coil 502 and leftcoil 503, respectively. FIG. 23B shows a wiring diagram of a three-arraytype choke coil in an arrangement that the respective ones are inpositive coupled structures. FIG. 23C is a projection perspective viewof a three-array type choke coil in a structure in that threeterminal-integrated type coils 501, 502, 503 are similarly arranged inline to be negative coupled structures. Likewise, theseterminal-integrated type coils 501, 503, 504, hereinafter, aredistinguishingly referred to as right coil 501, center coil 504 and leftcoil 503, respectively. In this structure, right coil 501 and left coil503, are both in the same winding direction, including center coil 504.FIG. 23D shows a wiring diagram of the array type choke coil. Note that,in FIGS. 23B and 23D, the power-supply connections at input terminal 20and output terminal 30 are respectively denoted as I1, I2, I3, O1, O2and O3.

Table 1 shows a result of inductance value L of each coil depending upona difference between positive coupled structure and negative coupledstructure of the coils in the present embodiment. TABLE 1 CoilArrangement and Magnetic Flux Coupling Structure Direction InductanceValue (μH) Coupling Positive Coupled FIG. 23A, Right Coil 501: 0.5798Structure Structure Center Coil 502: 0.5870 Left Coil 503: 0.5798Negative Coupled FIG. 23C, Right Coil 501: 0.5715 Structure Center Coil504: 0.5704 Left Coil 503: 0.5715

As understood from Table 1, the mean inductance value over the threecoils is greater in a positive coupled structure than in a negativecoupled structure arrangement. When attention is paid to center coil 502only, it is 0.5704 μH in a negative coupled structure which is smallerby −2.8% than 0.5870 μH in the case of a positive coupled structure.

As described in the above, also in the three-array type choke coil usingthree terminal-integrated type coils 501, 502, 503, inductance value Lcan be arbitrarily adjusted by a positive coupled structure, a negativecoupled structure or distance R between coil center points, similarly tothe case using two terminal-integrated type coils 50. Thus, optimaldesign can be easily done because inductance value L can be setaccording to the use purpose of an array type choke coil.

Although the present embodiment explained two-array type and three-arraytype structures, the present invention is not limited thereto. Theterminal-integrated type coils are ganged four or more into an in-linearrangement. Alternatively, arrangement may be on two rows or more byarranging a plurality of in-lined terminal-integrated type coils.

Moreover, at least one terminal-integrated type coil may be arranged ina position departing from a plurality of terminal-integrated type coilsarranged in line. FIG. 24A is a projection perspective view of an arraytype choke coil in which three terminal-integrated type coils 505, 506,507 having the same number of turns are arranged in a V-form on the sameplane to be a negative coupled structure. FIG. 24B is a side view of thesame while FIG. 24C is a wiring diagram. Terminal-integrated type coils505, 506, 507 are structured such that input terminals 5052, 5062, 5072and output terminals 5053, 5063, 5073 are exposed at the same direction,respectively. Such coils can be fabricated by etching or blanking ametal sheet, similarly to embodiment 1. In this manner, by alternatelyarranging a plurality of coils, it is possible to increase the chargeratio of the terminal-integrated type coils within magnetic material 7and reduce the size of the entire.

Meanwhile, in an array type choke coil structured as shown in FIG. 23A,it is possible to combine coils different in the number of turns. Forexample, FIG. 25 is a sectional view of an array type choke coil inwhich center points of terminal-integrated type coils are arranged inline. In this structure, terminal-integrated type coils 509, 510 havingthe number of turns of 2 turns and terminal-integrated type coil 508having the number of turns of 3 turns are arranged so that at the centerpoints of respective coils 508, 509, 510 are in line.

According to the present embodiment, regardless of the number of turnsor size, by making a plurality of coils into a positive coupledstructure or negative coupled structure or by adjusting the distancesbetween center points of the respective coils to thereby bury them inmagnetic material 7, inductance value can be accurately controlledcoping with design and, besides, a small-sized short structured arraytype choke coil can be realized.

In case an array type choke coil thus structured as a choke coil of apower supply circuit explained in FIG. 6 in embodiment 1, a largeinductance value can be obtained on an array type choke coilincorporating a plurality of terminal-integrated type coils in apositive coupled structure arrangement, for example. Accordingly, incase this is used as choke coil 63, a power supply circuit is possiblewhich can suppress ripple currents.

Meanwhile, in an array type choke coil incorporating a plurality ofterminal-integrated type coils in a negative coupled structurearrangement for example, it is easy to decrease the inductance value.Hence, a power supply circuit can be realized which corresponds to thegreater current. Such a power supply circuit is preferably used as apower supply circuit of a personal computer, a cellular telephone or thelike.

EMBODIMENT 5

FIG. 26 is a projection perspective view of an array type choke coilaccording to embodiment 5 of the present invention. In the presentembodiment, terminal-integrated type coils are used two in the numberand buried within magnetic material 607. First coil 601 is formedintegral with first input terminal 602 and first output terminal 603.Second coil 604 is similarly formed integral with second input terminal605 and second output terminal 606. Although the respective coils aredifferent in winding direction, the number of turns is 2.0 turns in theboth. Due to this, in the case of flowing currents to first coil 601 andsecond coil 604 through the respective first input terminal 602 andsecond input terminal 605, first coil 601 and second coil 604 haverespective in-coil magnetic fluxes different in directions.

Meanwhile, arrangement is such that the center axis of first coil 601and the center axis of second coil 604 are parallel and wherein twoturns of first coil 601 are in mesh with one turn of second coil 604.First coil 601 and second coil 604 are buried within magnetic material607. Magnetic material 607 is formed in a rectangular prism form. Bysuch an arrangement, first coil 601 and second coil 604 are allowed forbeing magnetically coupled.

In this manner, because the array type choke coil of the presentembodiment is a rectangular prism form, it is easy to handle the arraytype choke coil during automated mounting.

Here, explanation is made on a manufacturing method and concretestructure of a terminal-integrated type coil to be made into first coil601 and second coil 604, by using FIGS. 27 and 28.

At first, as shown in FIG. 27, fabricated is a blanked sheet having twoarcuate parts 631 formed by etching or blanking a metal sheet,connection 633 joining two arcuate parts 631 together and respectiveends 635 extended from one ends of two arcuate parts 631. The metalsheet is not especially limited provided that it is of a material low inresistance and high in heat conductivity, e.g., copper or silver.

Insulation film 632 is formed on a surface of two arcuate parts 631.This prevents a short circuit between arcuate parts 631 to be made intoa coil, in coil part 634 structured by folding and verticallysuperimposing two arcuate parts 631 of the blanked plate. Incidentally,no insulation film 632 is formed on a surface of connection 633. In thismanner, because insulation film 632 is provided in the region exceptingconnection 633, there is no occurrence of breakage, stripping or thelike in insulation film 632 even if connection 633 is bent. It ispossible to suppress the coil characteristic deterioration resultingfrom insulation film 632.

The blanked sheet is bent at connection 633 of two arcuate parts 631 ina manner so as to overlap center points with each other, as shown inFIG. 28. Thus, two arcuate parts 631 are made into coil part 634. Twoends 635 are provided radial about a center of coil part 634, to form aterminal-integrated type coil. In the present embodiment, because firstcoil 601 and second coil 604 are structured to place two turns of firstcoil 601 in mesh with one turn of second coil 604, respective coil parts634 are stacked with a gap in an amount of a thickness of arcuate part631.

By using such a blanked sheet, coil part 634 where arcuate parts 631 arestacked is insulation-treated with insulation film 632. Stacking ispossible without providing a gap between arcuate parts 631, enabling torealize an array type choke coil high in occupation area ratio.

Although FIGS. 27 and 28 show the case of 2 turns as aterminal-integrated type coil, easy fabrication is apparently possiblewith 3 turns or more by further increasing the number of arcuate parts631 in a blanked sheet state.

Incidentally, explanation is omitted concerning magnetic material 607because it can be fabricated of the material and by the method explainedin embodiment 1.

As for a manufacturing method of an array type choke coil shown in FIG.26, explanation is omitted similarly because fabrication is possible bythe same manufacturing method as embodiment 1.

FIG. 29 shows a sectional view along the line A3-A3 in an array typechoke coil shown in FIG. 26. First input terminal 602 and first outputterminal 603 of first coil 601 is formed extending along the line fromthe side to the bottom of magnetic material 607. Meanwhile, underlyinglayer 52 is formed in the part where first input terminal 602 and firstoutput terminal 603 are exposed at the surface of magnetic material 607.Uppermost layer 53 is formed in a manner so as to cover underlying layer52. Underlying layer 52 is preferably a nickel (Ni) layer formed byplating while uppermost layer 53 is preferably a solder layer or thin(Sn) layer. Those are similar to embodiment 1.

Due to this, because first input terminal 602, second input terminal605, first output terminal 603 and second output terminal 606 areformed, for example, with solder layers as uppermost layer 53, in therespective regions bent over the bottom of magnetic material 607, thearray type choke coil can be mounted more positively onto a printedboard or the like. Meanwhile, this provides a leadless structure, hencemounting with high density can be achieved.

In the array type choke coil of the present embodiment, first coil 601and second coil 604 are structured by blanking and bending of a metalsheet. Accordingly, as compared to the conventional coil structured bywinding a conductor wire and attaching a terminal at a tip of theconductor wire, it is easy to secure an inductance value and lowdirect-current resistance value required in a high-frequency region witha result that it becomes easy to cope with a large current.

Meanwhile, because a required inductance value can be secured withoutincreasing the number of turns of the coil, it is possible to realize asmall-sized short array type choke coil.

First coil 601 and second coil 604 are buried within magnetic material607. Magnetic material 607 is excellent in insulatability and capable ofpreventing a short circuit trouble between coils and at coil parts 634from occurring and realizing a reliable array type choke coil.Particularly, by providing magnetic material 607 containing one or moreselected from iron (Fe), nickel (Ni) and cobalt (Co) as a main componentof its metal magnetic powder, it is possible to obtain magnetic material607 having a high saturation magnetic flux density capable of copingwith large current and a magnetic characteristic of high magneticpermeability, thus realizing an array type choke coil great ininductance value.

The array type choke coil of the above structure is explained of itsoperation in the below.

First coil 601 and second coil 604 are equal in the number of turns butopposite in winding direction. Accordingly, in case flowing currentsthrough first input terminal 602 and second input terminal 605, themagnetic fluxes extending through the respective coils are opposite indirection due to the generated magnetic field. FIG. 30 is a sectionalview along the line B4-B4 in the array type choke coil of the presentembodiment shown in FIG. 26, showing the magnetic fluxes extendingthrough the respective coils denoted by the arrows. First coil 601 andsecond coil 604 have respective in-coil magnetic fluxes opposite indirection, thus providing a positive coupled structure.

FIG. 31 is similarly a sectional view along the line B4-B4 in the arraytype choke coil shown in FIG. 26, showing the magnetic fluxes extendingthrough the respective coils denoted by the arrows. In this case, firstcoil 601 inputs a current at first input terminal 602 while second coil604 inputs a current at second output terminal 606. The in-coil magneticflux of first coil 601 and the in-coil magnetic flux of second coil 604are the same in direction, thus providing a negative coupled structure.

The array type choke coil in the above structure is explained in itsoperation in the below.

As shown in FIG. 30, flow of an electric current to first coil 601causes a magnetic flux. The magnetic flux constitutes a magnetic circuitextending through the inside of first coil 71, to pass outside firstcoil 71 and return again inside first coil 71. During flow of currentsto second coil 604, a magnetic circuit is constituted similarly.

At this time, because first coil 601 and second coil 604 are arranged ina manner partly meshed, there exists a superimposed magnetic flux ofamong the magnetic fluxes of magnetic circuits caused by flow ofcurrents to first coil 601 and second coil 604. Particularly, themagnetic superimpositions are intensified at around the centers of therespective coils.

Namely, in the magnetic flux caused by flow of a current to first coil601, there is a magnetic flux extending through a coil inside of secondcoil 604. Likewise, in the magnetic flux caused by flow of a current tosecond coil 604, there is a magnetic flux extending through the insideof first coil 601. Because the direction of the magnetic flux extendingthrough the coil inside of first coil 601 and the direction of themagnetic flux extending through the coil inside of first coil 601 uponflow of a current to second coil 604 are the same, these aresuperimposed together to increase the magnetic flux extending throughthe coil inside of first coil 601. Because there is a similarsuperimposition concerning second coil 604, there is an increase of themagnetic flux extending through a coil inside of first coil 601.

This causes a great magnetic field through the array type choke coil,thereby increasing the inductance value furthermore. Accordingly, incase an array type choke coil in positive coupled structure is used as apower supply circuit choke coil 63 shown in FIG. 6 of embodiment 1, thepositive-coupled array type choke coil has an increased inductancevalue, thus suppressing the ripple currents and realizing a power supplycircuit capable of coping with a large current in a high-frequency band.

Meanwhile, on the array type choke coil structured shown in FIG. 31,flow of an electric current to the first coil 601 causes a magneticflux. The magnetic flux constitutes a magnetic circuit extending throughthe inside of first coil 601, to pass outside first coil 601 and returnagain to the inside of first coil 601. Furthermore, during flow of acurrent to second coil 604, a magnetic circuit is constituted similarly.At this time, because first coil 601 and second coil 604 are arranged ina manner partly meshed, there exists a superimposed magnetic flux ofamong the magnetic fluxes of magnetic circuits caused by flowingcurrents to first coil 601 and second coil 604. Particularly, themagnetic superimpositions are intensified at around the centers of therespective coils.

As shown in FIG. 31, of the magnetic flux caused by flow of a current tofirst coil 601, there is a magnetic flux extending through the inside ofsecond coil 604. Likewise, in the magnetic flux caused by flow of acurrent to second coil 604, there is a magnetic flux extending throughthe inside of first coil 601.

Because opposite are the direction of the magnetic flux extendingthrough the inside of the coil caused by flow of a current to secondcoil 604 and the direction of the magnetic flux extending through theinside of second coil 604 caused by flow of a current to first coil 601,there is a decrease in the magnetic flux extending through a coil insideof second coil 604. Similarly, because opposite are the direction of themagnetic flux extending through the inside of coil 601 caused by flow ofa current to first coil 601 and the direction of the magnetic fluxextending through the coil inside of first coil 601 caused upon flow ofa current to second coil 604, there is a decrease in the magnetic fluxextending through inside of second coil 604. This can reduce themagnetic field caused through the array type choke coil, thussuppressing the magnetic field from saturating.

Accordingly, in case the negative-coupled array type choke coil is usedsimilarly as a power supply circuit choke coil 63 shown in FIG. 6 ofembodiment 1, the direct-current superimposition of choke coil 63 can beincreased because magnetic flux saturation can be suppressed, thusrealizing a power supply circuit capable of coping with large current.

The inductance value of the array type choke coil is influenced by thecoupling state of first coil 601 and second coil 604. The coupling offirst coil 601 and second coil 604 changes depending upon thesuperimposition degree of magnetic-circuit magnetic flux caused byflowing currents to first coil 601 and second coil 604. Thesuperimposition can be changed by the arrangement of first coil 601 andsecond coil 604.

Accordingly, in case the distance is changed between a coil center pointof first coil 601 and a coil center point of second coil 604, the degreeof magnetic flux superimposition can be changed. As a result, theinductance value of the array type choke coil can be varied withoutchanging the number of turns of first coil 601 and second coil 604. Thiscan easily obtain the inductance value required in a design.

Hereunder, explanation is made on the relationship between distancebetween center points and coupling when changing the distance between acoil center point of first coil 601 and a coil center point of secondcoil 604, on the basis of a concrete example. In the below, first coil601 and second coil 604 is given an outer shape of 8.0 mm, an innerdiameter of 4.0 mm and a sheet thickness of 0.5 mm while magneticmaterial 607 is given a size of 10 mm vertically, 16 mm horizontally and3.5 mm in height.

FIG. 32A is a sectional view of an array type choke coil in a structurethat distance R between a center point of first coil 601 and a centerpoint of second coil 604 is R=6 mm. FIG. 32B is a similarly sectionalview in the case distance R between center points is R=7 mm while FIG.32C is in the case distance R between center points is R=8 mm. The basicstructure of these figures is a structure shown in FIG. 26, assuming asectional form in a manner extending along the line B4-B4. Meanwhile,FIG. 32D is a sectional view in the case distance R between centerpoints is R=0 mm. In this case, because the entire structure can be madesmaller in size, magnetic material 607 is made in a size smaller thanthe structure shown in FIG. 32A to 32C.

In the array type choke coil in a structure shown in FIG. 32A,concerning a mesh region by two coils, arcuate part 631 of second coil604 is in mesh between two arcuate parts 631 first coil 601. There isprovided an arrangement to put on one line all of the center points ofthe respective left-sided coil cross-sections of two arcuate parts 631comprising the coil parts of first coil 601 and all of the center pointsof the respective right-sided coil cross-sections of two arcuate parts631 comprising the coil parts of second coil 604. This is achievedbecause first coil 610 and second coil 604 are both given an outerdiameter of 8 mm, an inner diameter of 4 mm and a distance between coilcenter points of 6 mm, in the coil part.

In the array type choke coil in a structure shown in FIG. 32B,concerning a mesh region by the two coils, arcuate part 631 comprising acoil part of second coil 604 is in mesh with between two arcuate parts631 comprising coil parts of first coil 601. There is provided anarrangement to put on one line center points 641, 642 of the respectiveleft-sided coil cross-sections of two arcuate parts 631 comprising thecoil parts of first coil 601 and outer peripheries 645, 646 of therespective right-sided coil sections of two arcuate parts 631structuring the coil parts of second coil 604. This is achieved becausefirst coil 610 and second coil 604 are both given an outer diameter of 8mm, an inner diameter of 4 mm and a distance between coil center pointsof 7 mm.

In the array type choke coil in a structure shown in FIG. 32C,concerning a mesh region by the two coils, arcuate part 631 comprising acoil part of second coil 604 is partly overlapped between two arcuateparts 631 comprising coil parts of first coil 601. The degree ofsuperimposition is such that there is provided an arrangement to put onone line outer peripheries 647, 648 of the respective left-sided coilsections of two arcuate parts 631 comprising the coil parts of firstcoil 601 and of outer peripheries 645, 646 of the respective right-sidedcoil sections of two arcuate parts 631 comprising the coil parts ofsecond coil 604. This is achieved because first coil 610 and second coil604 are both given an outer diameter of 8 mm, an inner diameter of 4 mmand a distance between coil center points of 8 mm, in the coil part.

In the array type choke coil in a structure shown in FIG. 32D,concerning a mesh region by the two coils, there is provided anarrangement to completely overlap two arcuate parts 631 comprising thecoil parts of first coil 601 with two arcuate parts 631 comprising thecoil parts of second coil 604. Namely, there is provided an arrangementto put on one line center points 649, 650 of two arcuate parts 631comprising the coil parts of first coil 601 and center points 651, 652of two arcuate parts 631 comprising the coil parts of second coil 604.Incidentally, first coil 601 has a coil axis passing center points 649,650 of these two arcuate parts 631 while second coil 604 similarly has acoil axis passing center points 651, 652 of these two arcuate parts 631.This is because first coil 610 and second coil 604 are both given anouter diameter of 8 mm, an inner diameter of 4 mm and a distance betweencoil center points is 0 mm.

In the case of the structure of an array type choke coil shown in FIG.32A, the in-coil magnetic flux caused upon flow of a current to firstcoil 601 is not shielded by arcuate part 631 of second coil 604.Likewise, the magnetic flux in first coil 601 caused upon flow of acurrent to second coil 604 is not shielded by arcuate part 631 of firstcoil 601. Accordingly, in the array type choke coil of this structure,the magnetic path is not blocked by first coil 601 and second coil 604.As a result, it is possible to increase the effective cross-sectionalareas of coupling in the respective coils.

The array type choke coil of this structure is achieved not only in thecase the coils in mesh are quite equal in outer diameter and innerdiameter but also in the case the respective differences between outerand inner diameters of the coils in mesh are equal. For example, if thecoil part of first coil 601 has an outer diameter of 9 mm and an innerdiameter of 7 mm while the coil part of second coil 604 has an outerdiameter of 8 mm and an inner diameter of 6 mm, the distance between acoil center point of first coil 601 and a coil center point of secondcoil 604, if made 6.5 mm, can realize a highly-coupled array type chokecoil as above.

Incidentally, in the array type choke coil shown in FIG. 32A, thedistance between the center point of first coil 601 and center point ofsecond coil 604 was set such that respective center points 641, 642 ofthe left-sided cross-sections of two arcuate parts 631 comprising coilparts of first coil 601 and respective center points 643, 644 of theright-sided coil-sections of two arcuate parts 631 comprising coil partsof second coil 604 are all aligned on one line. However, such setting isnot necessarily required; i.e., it is satisfactory to make an alignmentto a degree to sufficiently secure an effective cross-sectional area ofin-coil coupling.

In the structure of the array type choke coil structure shown in FIG.32B, the in-coil magnetic flux of second coil 604 caused upon flow of acurrent to first coil 601 is partly shielded by arcuate part 631 of thecoil part of second coil 604. Likewise, the in-coil magnetic flux offirst coil 601 caused upon flow of a current to second coil 604 ispartly shielded by arcuate part 631 of the coil part of first coil 601.As a result, in the array type choke coil of this structure, there arecaused portions where magnetic paths are blocked respectively by firstcoil 601 and second coil 604. Accordingly, coupling can be suppressed ascompared to the array type choke coil in a structure shown in FIG. 32A.

In the structure of the array type choke coil structure shown in FIG.32C, the in-coil magnetic flux of second coil 604 caused upon flow of acurrent to first coil 601 is partly shielded by arcuate part 631 of thecoil part of second coil 604. Likewise, the in-coil magnetic flux offirst coil 601 caused upon flow of a current to second coil 604 ispartly shielded by arcuate part 631 of the coil part of first coil 601.As a result, in the array type choke coil of this structure, there arecaused portions where magnetic paths are blocked respectively by firstcoil 601 and second coil 604. Accordingly, coupling can be suppressedfurthermore as compared to the array type choke coil in a structureshown in FIG. 32A or FIG. 32B.

In the structure of the array type choke coil structure shown in FIG.32D, because there is provided an arrangement such that the coil partsof first coil 601 and second coil 604 have the same axis, size reductionas well as strengthening of the coupling is possible.

As described above, by changing the distance R between the coil centerpoint of first coil 601 and the coil center point of second coil 604,the effective cross-sectional area of coupling in the coil can beadjusted as well as the coupling degree. Accordingly, it is possible toadjust the total coupling of the array type choke coil more freely. Thiscan easily realize an array type choke coil having the inductance valuerequired in a design.

EMBODIMENT 6

FIGS. 33A and 33B are sectional views showing a structure of a coil partof an array type choke coil according to embodiment 9 of the presentinvention. This is a structure that two terminal-integrated type coils711, 712 are vertically arranged and buried within magnetic material713. Note that, in the figures, magnetic field direction is shown by thedotted-lined arrow while current direction is shown by the solid-linedarrow.

The array type choke coil in the structure shown in FIG. 33A isstructured that the respective coil parts 715, 716 of twoterminal-integrated type coils 711, 712 are vertically arranged andwherein currents are inputted at terminals such that the in-coilmagnetic fields caused upon flow of a current are in the same direction.This structure is positive coupling. By this structure, the occurringmagnetic fluxes are in the same direction. Because the respectivemagnetic fluxes are superimposed, inductance value can be increased andthe array type choke coil can be reduced in size.

Incidentally, similar effect is obtainable on three or moreterminal-integrated type coils if arranged similarly and inputted bycurrents through terminals in a similar manner such that in-coilmagnetic fields caused upon flow of a current are in the same direction.

An array type choke coil in a structure shown in FIG. 33B is structuredthat similarly two terminal-integrated type coils 711, 712 arevertically arranged to input a current from a terminal such that in-coilmagnetic fields caused upon flow of a current are in opposite directionsrespectively. This structure is negative coupling. Because the magneticfluxes caused are cancelled from each other by this structure, it ispossible to suppress against magnetic flux saturation and enhance thedirect-current superimposition characteristic of the array type chokecoil.

Incidentally, similar effect is obtainable on three or moreterminal-integrated type coils if arranged similarly and currents areinputted through terminals in a similar manner, such that in-coilmagnetic fields caused upon flow of a current are alternate indirection.

Concerning an array type choke coil in such a positive coupled structureand negative coupled structure, explanation is made on a relationshipbetween distance S between center points of two terminal-integrated typecoils 711, 712 and an inductance value. FIG. 34 is a relationshipbetween distance S between center points and inductance value L. Thisresult was determined on the assumption that terminal-integrated typecoil 711, 712 have a size of an inner diameter of 4.2 mm, an outerdiameter of 7.9 mm, a height of 1.7 mm and the number of turns of 3turns while a core formed of magnetic material 713 have a magneticpermeability of μ=26 and a size in vertical, horizontal and height of 10mm, 10 mm and 3.5 mm, respectively. Inductance value L was set to beL=0.595 μH.

In the case of distance S between center points of S=3.5 mm, the arraytype choke coil in a positive coupled structure had inductance value Lof L=0.747 μH while the array type choke coil in a negative coupledstructure had inductance value L of L=0.560 μH smaller by 24.9% than thecase of the positive coupled structure.

Similarly, in the case that distance S between center points was givenS=2.7 mm, the array type choke coil in a positive coupled structure hadinductance value L of L=0.794 μH while the array type choke coil in anegative coupled structure had inductance value L of L=0.468 μH smallerby 41.0% than the case of the positive coupled structure.

From the above result, it was found that, if distance S between centerpoints is equal, inductance value L is greater on the array type chokecoil in a positive coupled structure than on the array type choke coilin a negative coupled structure.

Meanwhile, in the case of changing distance S between center points in apositive coupled structure, L=0.747 μH was obtained at S=3.5 mm forexample while L=0.794 μH was obtained at S=2.7 mm. This value is 6.3%greater than inductance value L at S=3.5 mm. Likewise, in the case ofchanging distance S between center points in a negative coupledstructure, L=0.560 μH was obtained at S=3.5 mm for example while L=0.468μH was obtained at S=2.7 mm. This value is 16.6% smaller than inductancevalue L at S=3.5 mm.

From the above result, in the case of a positive coupled structure,inductance value L can be increased by arranging the coils in a mannerso as to shorten distance S between center points. Meanwhile, in thecase of a negative coupled structure, inductance value can be decreasedby arranging the coils in a manner so as to shorten distance S betweencenter points. Accordingly, without changing the number of turns of theterminal-integrated type coil 711, 712, inductance value L of an arraytype choke coil can be arbitrarily set to a certain extent by adjustingdistance S between center points.

Although explanation was made on the case with two terminal-integratedtype coils 711, 712, the inductance value of an array type choke coilcan be comparatively easily changed by adjusting the respectivedistances between center points in the case where three or moreterminal-integrated type coils are used.

FIG. 35 is a sectional view showing a modification to the array typechoke coil of the present embodiment. The array type choke coil of thismodification is a sectional view showing an arrangement structure ofterminal-integrated type coils 721, 722 having the number of turns of(N+0.5, where N is a natural number equal to or greater than 1), ofamong the array type choke coils arranging terminal-integrated typecoils in positive and negative couplings. Terminal-integrated type coils721, 722 are vertically stacked and buried within magnetic material 723.In FIG. 35, the terminal-integrated type coils respectively have thenumber of turns of 2.5 turns, wherein 2.5 turns of coil 722 is stackedon the right side of the 2 turns of coil 721. Meanwhile, 2 turns of coil722 is stacked on the left side of the 2.5 turns of coil 721. Thisstructure can realize an array type choke coil small in size and shortin structure because of the capability to eliminate useless space andstack coils with density.

In the below, explanation is made on the coil arrangement and thedirection of exposing input and output terminals of the array type chokecoil in the present embodiment like this.

FIG. 36A is a projection perspective view showing a structure thatterminal-integrated type coil 731 shown in FIG. 36B andterminal-integrated type coil 732 shown in FIG. 36C are verticallyarranged within magnetic material 730 in a rectangular prism form. FIG.36D is a wiring diagram of the same. Two coils 731, 732 respectivelyhave the number of turns of 1.5 turns, having respective input terminals733, 735 and respective output terminals 734, 736.

As understood from FIG. 36A, input terminal 733 of coil 731 and inputterminal 735 of coil 732 are exposed at the same surface, while outputterminal 734 of coil 731 and output terminal 736 of coil 732 are exposedat of the surface opposite to the above surface.

This arrangement can allow each of input terminals 733, 735 and outputterminals 734, 736 to be exposed at of the same surface. Accordingly,when mounting an array type choke coil onto a printed board, arrangementis facilitated in a circuit structure with a semiconductor integratedcircuit, etc, thus improving mounting density.

Meanwhile, it is easy to provide an indication, such as IN at input sideand OUT at output side. Although this modification had the number ofturns of 1.5 turns on two coils 731, 732, the similar effect isobtainable with the number of turns of 2.5 turns, 3.5 turns or the like.

Note that there is not always a need to expose all the input or outputterminals out of one surface, i.e., at least two of the input and outputterminals maybe exposed at one surface. Meanwhile, when exposing all theinput and output terminals at the same surface, the input and outputterminals may be exposed alternately.

FIG. 37A is a projection perspective view of an array type choke coil inanother structure. This array type choke coil is in a structurevertically arranging terminal-integrated type coil 741 shown in FIG. 37Band terminal-integrated type coil 742 shown in FIG. 37C. FIG. 37D is awiring diagram of the same. In the case of this array type choke coil,input terminal 743 and output terminal 744 of one coil 741 are exposedat the same surface of magnetic material 740 while input terminal 745and output terminal 746 of the other coil 742 are exposed at the surfaceopposite to the above surface.

In this structure, the coils are not limited to two in the number butthree or more coils may be stacked similarly.

FIG. 38A is a projection perspective view of an array type choke coil inanother structure. This array type choke coil is in a structurevertically arranging terminal-integrated type coil 751 shown in FIG. 38Band terminal-integrated type coil 752 shown in FIG. 38C. FIG. 38D is awiring diagram of the same. In the case of this array type choke coil,respective coils 751, 752 having the number of turns of 1.5 turns areburied in a wiring structure shown in FIG. 38D within magnetic material750. Namely, coil 751 has input terminal 755 and output terminal 756while coil 752 has input terminal 753 and output terminal 754. Coil 751and coil 752 are arranged to expose the respective input terminal 753,755 and the respective output terminal 754, 756 out of differentsurfaces.

This structure prevents the terminals from contacting one with anothereven if the input and output terminals are increased in area.Accordingly, the mounting on or heat dissipation to a printed board canbe improved furthermore, and further the terminals can be lowered inresistance value, hence realizing an array type choke coil coping withcurrent increase.

Meanwhile, because this structure can evenly disperse the terminalsoldering points, mounting strength can be increased.

In the array type choke coil of this structure, the coils are notlimited to two in the number but three or more coils may be stacked in asimilar way. In such a case, arrangement is possible to allow aplurality of terminals to be exposed at the same surface.

Although the magnetic material was explained as in a rectangular prismform, chamfering may be made to facilitate directional determination orindications may be provided indicating input and output terminals.

As described above, the array type choke coil of the present embodimentcan secure a required inductance value in a high-frequency band, hold asmall direct-current resistance value, and cope with large current, thusbeing reduced in size. Accordingly, the use on a power supply circuit asexplained in FIG. 6 of embodiment 1 can realize a power supply circuitsmall in size and high in performance. This power supply circuit ispreferably mounted on an electronic apparatus such as a personalcomputer or a cellular phones, enabling size reduction.

EMBODIMENT 7

An array type choke coil in embodiment 7 of the present invention isexplained while referring to FIGS. 39 to 41. The array type choke coilof this embodiment is similar in basic structure to the array type chokecoil explained in embodiment 1 to 6. FIGS. 39 to 41 shows an exteriorview of the array type choke coil, wherein terminal-integrated typecoils are shown at input and output terminals only.

The array type choke coil shown in FIG. 39 is characterized by astructure that all input terminals 151 are exposed out of one surface ofmagnetic material 7 in a rectangular prism form while output terminals(not shown) are all exposed out of the surface opposite to the onesurface. Due to this, when the array type choke coil is mounted onto aprinted board, it can be arranged close to a semiconductor integratedcircuit or the like, thus making it possible to enhance the mountingdensity on a printed board. On the top surface of magnetic material 7,there is provided indication area 121 where IN-1, IN-2, IN-3, etc. arewritten by printing or the like as indications representative of inputterminals 151, and OUT-1, OUT-2, OUT-3, etc. as indicationsrepresentative of output terminals. Due to this, it is easy to easilyconfirm in mounting onto a printed board for example or after mountingwhether an array type choke coil has been mounted correctly.

Incidentally, structure may be that input and output terminals are allexposed out of one surface. For example, input terminals 161 and outputterminals 162 may be alternately arranged and exposed as shown in FIG.40. In this case, on the top surface of magnetic material 7, there isprovided indication area 121 where IN-1, IN-2, IN-3, etc. are indicatedin respective corresponding positions by printing or the like asindications representative of input terminals 151, and OUT-1, OUT-2,OUT-3, etc. as indications representative of output terminals 162. Dueto this, it is easy to easily confirm in mounting onto a printed boardfor example or after mounting whether an array type choke coil has beenmounted correctly.

There is not necessarily a need to expose all input terminals 161 andoutput terminals 162 out of one surface. At least two terminals selectedfrom two or more input and output terminals may be exposed out of onesurface.

In the case of a terminal-integrated type coil having the number ofturns of N turns (N is an integer equal to or greater than 1), thestructure is that the input and output terminals project at the upperand lower positions in the same direction. The input and outputterminals, in upper-and-lower sets as they are, may respectively bearranged on one surface.

Furthermore, coil arrangement is possible such that at least twoterminals are exposed in respective different directions. For example,the array type choke coil shown in FIG. 41 is structured that threeoutput terminals 172 are exposed at respective different surfaces whilethree input terminals 171 are all exposed at the same surface. In thecase of this array type choke coil, on the top surface of magneticmaterial 7, there is provided indication area 121 where IN-1, IN-2,IN-3, etc. are written in respective corresponding positions by printingor the like as indications representative of input terminals 171, andOUT-1, OUT-2, OUT-3, etc. as indications representative of outputterminals 172. Due to this, it is easy to easily confirm in mountingonto a printed board for example or after mounting whether an array typechoke coil has been mounted correctly.

Although the above structure explains the case using terminal-integratedtype coils three in the number, there is no limitation in the number ofterminal integrated type coils. There is no limitation also in thedirection in which terminals are to be taken out. It is satisfactory ifexposure is done in the plane in the direction in which terminals are tobe exposed.

In this manner, in the case of a terminal-integrated type coilarrangement having terminals exposed an arbitrary plane, it is possibleto increase the distance between terminals. This can increase terminalarea and hence improve heat dissipation characteristic furthermore.Because the terminal can be reduced in resistance value, it is possibleto realize an array type choke coil that is suited to current increase.Because the terminal soldering points are dispersed in the bottom andits vicinity by such a structure, mounting strength can be increasedagainst force in each direction. Incidentally, although the magneticmaterial was in a rectangular prism form in the present embodiment, acorner may be removed from a side in a part or indications may befurther provided on the respective terminals.

INDUSTRIAL APPLICABILITY

The array type choke coil of the present invention is structured byfabricating terminal-integrated type coils through bending a blankedsheet formed by etching, blanking or the like a metal sheet, and buryingwithin a magnetic material the terminal-integrated type coils inplurality so as to have a predetermined positional relationship. Becauseit can be used in a high-frequency band and a required inductance valuecan be secured and a small direct-current resistance value can be held,it is useful for various electronic apparatuses, particularly in thearea of portable apparatuses such as cellular telephone.

1. An array type choke coil characterized by comprising: a coil grouparranging a plurality of terminal-integrated type coils formed bybending a metal sheet in a preset development form and having a setpositional relationship; and a magnetic material burying therein thecoil group.
 2. An array type choke coil according to claim 1, whereinthe coil group structure arranges the axes of coil constituting the coilgroup in parallel, where the center point of at least one coil selectedfrom the plurality of coils and the center point of a coil other thanthe selected coil are in a staggered arrangement.
 3. An array type chokecoil according to claim 2, wherein a predetermined inductance value isobtained by changing the distance between the center point of at leastone coil selected from the coil group and a center point of at least onecoil selected from the plurality of coils other than the selected coil.4. An array type choke coil according to claim 2, wherein apredetermined inductance value is obtained by changing the height of acenter point of at least one coil selected from the coil group and acenter point of at least one coil selected from the plurality of coilsother than the selected coil.
 5. An array type choke coil according toclaim 2, wherein at least one coil selected from the coil group and bothcoils immediately adjacent to the selected coil are in a V-form orinverted V-form arrangement, to make a direction of magnetic fluxextending through the coil caused upon flow of a current to the selectedcoil and a direction of magnetic flux extending through the coil causedupon flow of a current to the two coils arranged immediately adjacentdifferent in direction from each other.
 6. An array type choke coilaccording to claim 2, wherein at least one coil selected from the coilgroup and both coils immediately adjacent to the selected coil are in aV-form or inverted V-form arrangement, to make a direction of a magneticflux caused upon flow of a current to the selected coil and a directionof magnetic flux caused upon flow of a current to the two coils arrangedimmediately adjacent the same in direction.
 7. An array type choke coilaccording to claim 2, wherein the coils constituting the coil group havethe number of turns of (N+0.5) turns (where N is an integer equal to orgreater than 1), to provide an arrangement structure stacking an N-turnportion of the coil selected from the coil group and an (N+0.5)-turnportion of the coil immediately adjacent to the selected coil.
 8. Anarray type choke coil according to claim 5, wherein a predeterminedinductance value is obtained by changing respective distances between acenter point of the coil selected and center points of the both coilsarranged immediately adjacent.
 9. An array type choke coil according toclaim 1, wherein the coil group arranges the coils such that centerpoints of the plurality of coils constituting the coil group are on asame plane.
 10. An array type choke coil according to claim 9, wherein apredetermined inductance value is obtained by changing the distancebetween center points of two coils immediately adjacent among theplurality of coils.
 11. An array type choke coil according to claim 9,wherein the coil group is arranged such that magnetic fluxes in thecoils caused upon flow of currents to the plurality of coils alternatein direction.
 12. An array type choke coil according to claim 9, whereinthe coil group is arranged such that magnetic fluxes in the coils causedupon flow of currents to the plurality of coils are same in direction.13. An array type choke coil according to claim 1, wherein the coilgroup structure arranges the axes of coils constituting the coil groupin parallel, having a distance between the center point of at least onecoil selected from the plurality of coils and the center point of a coilimmediately adjacent to the selected coil is half or smaller than thesum of the outer diameter of the selected coil and the diameter of theadjacent coil, wherein at least one turn portion of the selected coil isarranged in a manner meshing with the adjacent coil.
 14. An array typechoke coil according to claim 13, wherein the selected coil and theadjacent coil have the number of turns of N turn (where N is an integerequal to or greater than 2), to provide an arrangement such that (N−1)turn portion of the adjacent coil is in mesh with the selected coil. 15.An array type choke coil according to claim 13, wherein the coil groupis arranged such that the difference between the outer diameter and theinner diameter of the selected coil and a difference between the outerdiameter and the inner diameter of the adjacent coil are equal, and thedistance between the center point of the selected coil and the centerpoint of the adjacent coil coincides with half of the sum of the outerdiameter of the selected coil and the inner diameter of the adjacentcoil.
 16. An array type choke coil according to claim 13, wherein apredetermined inductance value is obtained by changing the distancebetween the center point of at least one coil selected from the coilgroup and the center point of a coil adjacent to the selected coil. 17.An array type choke coil according to claim 13, wherein the coil groupis arranged such that the direction of magnetic flux in a coil of uponflow of a current to at least one coil selected from the coil group andthe direction of magnetic flux upon flow of a current to a coil adjacentthe selected coil are same in direction.
 18. An array type choke coilaccording to claim 13, wherein the coil group is arranged such that thedirection of magnetic flux in a coil of upon flowing a current to atleast one coil selected from the coil group and the direction ofmagnetic flux upon flow of a current to a coil adjacent the selectedcoil are different.
 19. An array type choke coil according to claim 9,wherein the coil group structure arranges the plurality of coils all inline.
 20. An array type choke coil according to claim 1, wherein atleast one coil selected from the plurality of coils is arranged in aposition deviated from the other coils arranged in line.
 21. An arraytype choke coil according to claim 1, wherein the coil group is arrangedsuch that selected two or more input terminals or selected two or moreoutput terminals or both are arranged exposed at a same surface.
 22. Anarray type choke coil according to claim 1, wherein the coil group hasthe plurality of coils constituting the coil group buried within themagnetic material.
 23. An array type choke coil according to claim 22,wherein a predetermined inductance value is obtained by changing theintervals between the plurality of coils.
 24. An array type choke coilaccording to claim 22, wherein the coil group is arranged such thatmagnetic fluxes in the coils caused upon flow of currents to theplurality of coils are in the same direction.
 25. An array type chokecoil according to claim 22, wherein the coil group is arranged such thatmagnetic fluxes in the coils caused upon flow of currents to theplurality of coils alternately in direction.
 26. An array type chokecoil according to claim 22, wherein the plurality of coils have thenumber of turns of (N+0.5) turns (where N is an integer equal to orgreater than 1), to provide an arrangement structure where coils inupper and lower positions have respective Ot5 turn portions lying on asame plane.
 27. An array type choke coil according to claim 22, whereinall of the input terminals or all of the output terminals of theplurality of coils or both are exposed at the same surface.
 28. An arraytype choke coil according to claim 1, wherein the magnetic material isformed from at least one of the group consisting of a ferrite magneticmaterial, a composite of a ferrite magnetic powder and an insulatingresin and a composite of a metal magnetic powder and an insulatingresin.
 29. An array type choke coil according to claim 1, wherein aninsulation film is formed on the surface of the coil.
 30. An array typechoke coil according to claim 1, wherein the coil group has at least twoterminals exposed at respective different surfaces.
 31. An array typechoke coil according to claim 1, wherein the coil group has at least oneterminal exposed at least two surfaces the bottom surface and thesurrounding surface thereof.
 32. An array type choke coil according toclaim 1, wherein the coil group terminal portions which are exposed atthe surface have a substrate layer containing nickel (Ni) or a nickel(Ni), and an uppermost layer which is formed of a solder layer or thin(Sn) layer.
 33. An array type choke coil according to claim 1, whereinthe magnetic material is provided with an indication area indicative ofthe input terminals or output terminals or both.
 34. An array type chokecoil according to claim 1, wherein the magnetic material is formed in arectangular prism form.
 35. An electronic apparatus characterized bymounting an array type choke coil according to claim
 1. 36. An arraytype choke coil according to claim 6, wherein a predetermined inductancevalue is obtained by changing respective distances between a centerpoint of the coil selected and center points of the both coils arrangedimmediately adjacent.
 37. An array type choke coil according to claim13, wherein the coil group structure arranges the plurality of coils allin line.